The Children's Hospital of Philadelphia (CHOP), in collaboration with the Center for Clinical Epidemiology and Biostatistics (CCEB) at the University of Pennsylvania, proposes to develop an innovative research training program in pediatric pharmacoepidemiology, specifically designed to train pediatricians to be rigorous, independent academic investigators able to use the range of approaches available in epidemiology to study the use and effects of medications in pediatric patients. The specific aims of the training program are to: 1) provide in-depth knowledge of the research techniques appropriate to clinical pharmacoepidemiology research; 2) apply these research techniques to pediatric populations; 3) provide an understanding of the basic principles of clinical pharmacology and how these principles apply to pediatric patients; 4) provide opportunities for the study of topics related to pharmacoepidemiology in a pediatric setting; 5) provide research experience with mentors in pediatric pharmacoepidemiology; and 6) bring together faculty and fellows through seminar series at CHOP and at the CCEB. Trainees will earn a Master of Science in Clinical Epidemiology (MSCE) degree from the CCEB. This multidisciplinary, two- to three-year training program consists of core courses in epidemiology, clinical research methodology, and biostatistics; required courses in pharmacoepidemiology and pharmacokinetics; elective courses in advanced methods for epidemiology and biostatistics, and/or pharmacology; a required clinical experience in pediatric pharmacoepidemiology; a teaching seminar series; instruction in the responsible conduct of research and regulatory affairs; extensive independent readings and attendance at research seminars at CHOP and the CCEB; and applied research in pediatric pharmacoepidemiology under the close supervision of a senior mentor. Strengths of the proposed program are: 1) the long history of successful research training programs in the CCEB and CHOP; 2) the collaborative links that have been forged among the faculty between these academic entities; 3) the comprehensive course offerings and research programs that are available to trainees; 4) the internationally renowned pharmacoepidemiology program housed in the CCEB; 5) the wealth of databases available at CHOP for pharmacoepidemiologic analyses; and 6) the extensive successful training records of the program director and faculty.